Apparatus for mine roof control



March 18, 1958 J. F. JOY

vAPPARATUS FOR MINE ROOF CONTROL Original Filed Oct. 6, 1948 3Sheets-Sheet 1 A Oliv 4 N MS March 18, 1958 J. F.JoY

APPARATUS FOR MINE ROOF CONTROL Original Filed Oct. e, 194s 3Sheets-Sheet 2 65N@ .NN QS,

1522/622262# ToseJv I.' Joy any.

March 18, 1958 J. F. JoY 2,826,898

APPgRATUs FOR MINE: ROOF CONTROL l original Filed oct. e, 1948 5sheets-sheet s 22 Eig 4- /49 22 may United States Patente@ 2,825,598..APPARATUS @Fone MINE `Roon-coisifrnonfacturng Company, Ritfsburgh;,Pa.,a.corporation of PennsylvaniaY v Original application October 6, 19.485,SelalfNo. 53,lulll,

nowPatent;N.2,152,757, .datedzlulnf 19.156 Dl- This invention relates toapparatusgfor mine roof conf` trolj-and more particularly-to animprovedV hydraulicallyoperated Walkingnjack mechanismhaving"rollingontacte with the mine door and root for supportingjthelatter;

An object ofthe invention is'to-provide an improvedy roof support: foran underground mine; Anotherobjectis to provide'animprovedroofsupporting structure'having means Vincorporated therein-for`facilitating litsmbeing;l progressively advanced, along with `theadvance of amine facefwithoutl substantial release of the resistancetoroof subsidence and with suieient 'yield'l providedq for antw maticallyto -accornmodateat le astjniinor localsubsi-l denc:es. vk Still anotherobject is to provide improvedme-l chanically actuatedstructures forpthecontrollofmipe,

roofs whichr support 'the roofclose up to-theface along,

Yet another object is to provide aniniproyedroof"jaeley mechanismyhaving improved means for'a1teriug-its--1ine` of advance. Other objectsand advantages of there-inven-A tion will hereinafter4 more fullyappear.4

Thisv application is a divi sion of fmyjcopending application Serial No.53,070, filed October 6, l948,"nowrn`1a tured into Patent No. 2;752,757,dated'July--3,".1956;`-

In the accompanying ydrawingsin whichY- forpurposes` of illustrationthere is shown anr embodiment which'lfthe invention may assume inpractice: p

Fig.1 is a plan viewof ankillustrative embodimenteof the improvedrootjacle structure.-

Fig. 2 is a side elevational view of the structure shown in Fig- 1.vv

Fig. `3 is `an enlarged vertical sectional view= taken-on the plane ofline 3 3 ofvFig. 1.

Fig.-4 is a-somewhatdiagrammatic vview showingfthe ui'd pressureoperating sources and connectionswffo'r effecting the roof supportingand 1walking;.operation :of the jacksf Fig. `5 is' air-agmentarysectional. iview: through; theibotf tom end of a pump used tosupply-Huidto-thetrooffsupe porting jacks.

In4 the-illustrative `construction,-.as shownfin theqdrawfS ings; theimproved walkingroofsupporting jacks comprise two upperandI ltwo =lowerframes .havingroof andi lloor engaging-'devices on them.. one longupper: lframe :at each side, and onevlonglower -framerat each-sidei'andeachof the ljacl: deviceszl and 2 has-iupperfand lowery transverselyextending frames 'rigidlyr connected atioppositeendscwith A,furtherobject isuto provide anirnproved"y 2,826,898 ice Patented`Mer..,18,k 1953 elongated longitudinally extending;-` guide Yv frames 4:

Thjere are; thus twoy upper guide -franjies anda-two'. lower guide-framesthe frames -Vof -each-pair being-spaced Ibythe width of the crossframes \frorn-eachl-other.- The" guider-frames 4 may be of` any suitable@con-struction;- for example,t of frail-orgenerally'I-beamconstruction-5^A being' herein- 4shown as-'formed by rigid yrailV#sections With-semifcireular guide elements 5 fattheiroppositeends,-theguide" elements 5-at-one end of:each-guideV frame-being`rela-1V tivelyJfadjustablelto insure suitable tension forY the rollerconnecting elements'shortly to besdescribed. l The lowery frames 4 haveshallow Ichannel sections 6 suitablyvsecuredg as by welding :orotherwise, to 1 their# heads-and have their basel lflanges provided with:side ledges-T to provideJ forA the later-al i guiding Vof a` series -of{rollers-8 f-.which'iare adapted to provide a` rolling support-tortherlower frames- 4-as the -jacklinechanism is advanced..l Theinvertedupper railr 'elements Aoifthe* upper rframes 4 l1fave-v sideledges -9fat th'eiritopstov-guidethetfassociated rollersk 8,and to support thelower-run of.-'rollers'-associatedywith the upper-guide frame-=4;fthereisdisposed beneath-them and spaeedbe neath1gthe-bott-omofeachupper-guiderframe," an elond4 gatedliguide'astrip or-channel bar-;10which; ishheld'fin -the desired spaced relation kto -themframe 4whichfis above it;

byzspacing platessll'fsecuredv tol the-guide bars iandto thesides-oi--the frames `'-lsf The rollers Suarefprovidedwithfy throughpinsl21`fand between thesezpins andthef-rolle'rsf therearemountedsuitable bearings' (notshown): TheA oppositefendsoit-itli'etpinsl are :suitably-bored,-i ,asvrshpowneine Fig 3,at13,tolpermitl anendl'ess cabl'er141to1extend through/thevvariousopenings-fandy provide'a connectionf between the rollers, andin'order-thatfth'e rollers Imay notcontact witheachottieni-these-pinsmayfbe'iiitcd-inspacedz apart-^relation tothecable loop--as by axial clamping screws 15.

Thel devices or--extendingf-thejack elements-fthe deA vicesrfor-feedingthem;etc.v--includes---the =front-andrearroofSi load-sustaining v-'jackldevices 11'andv=2, anfuprighg abutment jack device generally.ldesignated 16?i anY-ex-` tendible Awalking jack device generallyJdesignated--17 for-A impartingh repositioning forces to the jackdevices, will now "be described. f It: Vwill be v observed-that many ofthe parts ofthe frontandrear fja'ckdeviccsware Kidentical;v and,therefore ya-detailr description'fxof Jthefgjackidevice lwillfysuiii'cel forsboth jackdevice's. I The jack: device issh'own as -ofthelhydraulic'pressure operated type-aand f-is carriedby alowervetran-sversely Vextending'framelorcrossframe memberg '-andincludes, asy -fully`vdisclosed inf the copend-v ing-applicationY.Serial No.. 53,070,- now= Patent-No 2,75 2,757, a vertical cylinderY-19 in" -whichi` a hollow/pistoni element-2li -'is reciprocable.` The vreciproc-ableihol-low Lpiston has-an-upper-head 21havingaboss-ionprojectionfZZI looselyv received in an opening- 23forrned'inatopewalllof` the upper 1transversely-extendingframe3; T hepiston has rigidly secured thereto at its lower; end a suitably packedpiston head-124; The piston head isi recessedlat ZSIat'its lower-,sideand-a passage :2 61extends from thislrecess throughv the rupper surfaceof the piston l24, 'fand ya member 27threaded'within thepistoni-provides amounting fo`ra conventional. accumulator zfwhichimaybe, for exampley of theiG're'eritypefv Liquid may owfrornthepassage 26tothe interioriofthe lflexible' rubber` bag-foffthe?accumu-l latort Asuit`able iillingconnection 291to1'.ithei-'accurnuf-Elatoi-isnprovidedat the top of: the.faccumulatorll'whereby` the latterk-maymbefpreloaded with gaseous.A Huid' from` `an externalI supply..y Theother roof-support 421isfoiz'fa vsimilari construction.- Liquid under4pressurefmaybe supplied :to the hydraulic` jacks by aconventional-.handfoperatedipumpY mechanismwhich is connectedto. aliquidreservoir-orV tank 31u `The `entendible*,jack'dev-ice*.17 isinthefoljm-Of aait/allie. ingjaelemeehanisxn,including `21l1orizontal,longitudinally extending cylinder 33 containing a reciprocable piston 34having its piston rod 35 connected at 36 with a boss 37 on a collarlikeelement 38 surrounding the cylinder of the abutment jack device 16. Thecylinder head 39 is pivotally connected at 40 with a collar 41surrounding the cylinder element 19 thereby to enable the cylinderelement to swing vertically.

The abutment jack device 16 includes a vertical cylinder 43 closed atits bottom at 44 and having a mine floor engaging support element 45.Within the cylinder there is reciprocable a piston 46 having itsupstanding tubular piston rod 47 carrying a roof engaging element 48 atits upper end. Liquid may be admitted to and vented lfrom the cylinderbeneath the piston through a conduit 49.

Liquid may be supplied to the liquid supply conduit 49 through a passage50 formed in the cylinder head 39 of the walking jack and leading to thebore of a conducting tube 51 mounted within the cylinder head 39 andvtele scoping with the hollow piston rod 3S which receives the tube.Liquid may be admitted to the opposite ends of the bore of the cylinder33 through conduits 52 and 53 formed in the cylinder heads respectively.Each of the liquid supply connections 50, 52 and 53 will desirably beequipped with a fitting through which liquid can be supplied to it pasta stop valve, as fully disclosed in my copending application abovereferred to.

In view ofthe tact that the abutment jack device 16 and the walking jackdevice 17 will have liquid supplied to them and vented from them only onthe order of perhaps once or twice, or at most a very small number oftimes, a day, it is unnecessary to provide liquid reservoirs and pumpsindividual to them, and instead a portable liquid supply and dischargearrangement such as is shown in my Patent No. 1,900,446 may be providedto supply liquid under pressure to extend the abutment jack device 16and to move the cylinder 33 relative to the abutment jack, or to allowthe venting of liquid; it being understood with respect tothe walkingjack device 17 that it will be necessary to provide a return connectionfrom whichever one of the connections 52 or 53 is not to have liquiddischarged to it from the apparatus shown in said Joy patent. Such aliquid supply means is portable from jack to jack.

It may be noted that the abutment jack device 16 may be repositionedlaterally, as indicated in dotted lines in Fig. 1, so as to cause thejack devices to change their direction of travel, that is, to be movedslightly laterally in one direction or the other as they advance towardthe face. l It will be understood that the loose mountings of the upperframes 4 on the jack devices 1 and 2 permit limited lateral andlongitudinal tilting ot' the solid upper frame structure including twoframes 3 and two frames 4.

In Fig. 4, there is shown for purposes of illustration, a controldiagram. This diagram shows the connections so far mentioned, and alsoothers. The roof jack devices are shown at 1 and 2, the abutment jackdevice at 16, and the jack device for effecting walking is shown at 17.The abutment jack and the walking devices are adapted to be suppliedwith liquid under pressure from a separate power driven pump device 55,such as is shown in my Patent No. 1,900,446.`- The only materialdifference between the device of the patent and the device shown at 55resides in the fact that a return conduit or connection 56 is providedfor the back ow of liquid from a working space which is to be vented tothe reservoir of the device 55, and of course the reservoir size and thedischarge pressure will be predetermined to the demands of the work tobe done. If desired an adjustably loaded relief valve 57 may be arrangedbetween the discharge conduit 58 from the device 55 and the return lineto the reservoir. Each of the connections 50, 52 and 53 will be providedwith a stop valve (shown in Fig. 4 at 59, 60 and 61), and suitable quickdetachable connections, as of the Hansen coupling type, may be providedto facilitate connection and disconnection between the condiuts 56 and58 and the connections 52 and 53.

The liquid supply to the roof jack devices 1 and 2 is, as has beenpreviously noted, such that liquid under pressure may be suppliedsimultaneously to them, as will ordinarily be desirable, or separately,and liquid may also be vented simultaneously or separately from them.The manually operable pump mechanism 30 includes, as has been noted, areservoir 31, a pump cylinder 62 and manual operating means 63 for thepump. An operator may therefore quickly pump up the desired pressures inthe jack devices 1 and 2.

The supply of liquid under pressure to the cylinders 19of the jackdevices 1 and 2 beneath the pistons 24 is by the hand operated pumpmechanism 3), and a shelf 64 carried by the frame 3 supports the pumpmechanism. This pump mechanism may be of any suitable construction and,as shown, includes the reservoir or liquid tank 31, and the `pumpcylinder 62 in which a plunger 65 is adapted to be reciprocated by theoperating means 63. The bottom of the pump cylinder communicates througha passage 66 (Fig. 5) with a chamber 67 which is arranged between a pairof check valves 68 and 69. The check valve 69 controls communicationwith the discharge line 70, which opens into a valve casing 71. Thecheck valve 63 controls communication between the reservoir V31 and thechamber 67. The valve casing 71 contains a valve (not shown) shiftableto connect the line with a conduit 72, leading to the bore of thecylinder of the jack 1 beneath the piston, or to connect the line 70with a conduit 73 leading` to the cylinder bore of the jack mechanism 2,or to connect the line 70 with both conduits at the same time. A returnconnection from the line 70 to the reservoir is provided at 74 and iscontrolled by a valve 75. The reservoir has a supply connection 76, andadditional liquid will be supplied to the reservoir, as needed, whilethe jack devices are being extended to provide approximately the desiredelevation of their upper portions. Means for releasing pressure from thebores of the cylinders beneath the pistons in the event of excessiveroof pressures is provide-d in the form of two relief valve controlmeans 77 and 78, these having the relief valves therein set at pressureshigher than any normally desired pressure in the cylinder bores beneaththe pistons but adapted to permit the return of liquid from these boresthrough a common conduit79 to the line 74 as pressures such as toendanger the accumulators 28 are occasioned by markedly increased 4roofpressure.

The upper andlower roller carrying frames 4 associated with the roofsupporting jacks 1 and 2 arc connected together by the cross frames 3and extensible parts of the roof supporting jacks and clue to themultiplicity of rollers and the substantial length of the up- `per andlower beamlike frames the pressure per square inch of contact with thefloor and roof is substantially reduced, and yet these roller frames arecapable of rolling along the oor and roof without excessive forces beingrequired. Thus the roof supporting jack devices 1 and 2 are connectedtogether by the upper and lower' frames and the cross frames so thatforward movement of one jack device will be attended by correspondingmovement of the other jack device and yet, if there is uneven subsidenceof the roof, there may be limited tilting of the upper frames relativeto the jack devices. Change in the direction of jack travel may also befacilitated, as` mentioned above.

When the roof supporting apparatus is in roof supporting position, asshown in Fig. 2, the roof supporting jack devices 1 and 2 will besubjected to hydraulic pressure from the pump mechanism 30 in suchmanner that they will provide the desired roof support, and the forceswill be applied to the roof through the series of roof contactingrollers 8, resulting in a substantial area of contact between the upperroof supports and the roof forced. .intostheaccumulator, lincreasingthe.- pressurent theconlnedgaseous iluidin-` the vacc un1ulator bag. andtherebylin many cases enabling; continued nonerigid withstanding ofincreased roof'v pressurer, Whenrtlre, roofA jacl; underlyingthegarea;of increased;pressuresis ad; vanced from beneath .I thatzareaathefgaseous uid :under increased pressure in thenaccumulaton'bagwill displace liquid from the f accumulator and cause, the return. ofthe roofv engaging portions 0f the jaekgzdevice tto its previo/us.v leve l. Of cou1 se,4 as. -has been; ;previously explained; before thepressurecould ghe/ built up in. thetaccumulators sufiicient to rupture.thebags therein,thetreliefnvalve means heretofore describedintheconnections?? iand/ on 78 would allow the,escapeiof1fluidand.thesubstitutionj of asolid yfora yielding support fori the .roofApressures The provision of the .yielding support of course,.facili-ttates the advance ofthe jacks overuneven bottornruor. beneathunevenroof.\ Further explanationcitheimodef of operation and advantagesoftheinventionisclearly unnecessary, since the manner of, extendingthejack def viceofthe roof-supporting jackimechanisms,thernanner` o fextending and -collapsing they abutment, v jack device 16 andthemannerof ,supplying ,the lluid to the oppositel en dsoflthe walkingjackdevicellfwillV be clearlyxap.- parentfrom vthe description already givemA sfa ,result of this invention an improvedpmine .roof supportingapparatus is provided having animproved arrangement ofthe `oor engagingand roofv supporting roller-carrying supports. By the .provision.r,ofthelrigid, longitudinally extendingl elongated beam Amembers .forcarrying the rollers, and 'the associated supporting parts, theirnineAroof is at all times adequately ysupported while the apparatus withoutrelease ther eof may bei readily; advanced as the .minevfaceadvances TheprQi/iSionofl theabutment jack, together withthehorizontally swingablewalking jackconnected thereto, enable the roof` supporting apparatus tobe advanced in variousdirec.. tions as determined by thelateralpositionofthe ahnte mentv jac l Thetstructure is relatively simpleandrugged iiidesign, and extremely cornpact,l well adapted fortits,xintendempurpose, Otheradvantages Y-of'- the invention WilL-,b clearly)apparentto those skilled, in the art.-

While there is; in; this application,v specicallydescribed-4 onet fo r mwhich L,the f invention may assumein practice, it; will .bei understood:that` thiszformof thesame. ist shown for purposes of, illustration andthat the; invention may be. rnodie d anden1hoded -in i various, other.forms ,withf` out departing from its;r spirit or the. scopeof the;appended. ClELlLIl'lS-pl Y i Whatl claimfrasnewzand, desire to securebyLetters; Patentris:

1a Ina mine rooiisupprorfting jack mechanisrma ,pain @f elongated,substantially vcoextensiveand superimposed roof and floor engaging;devices,v eachilofusaid., devices iacludinafan eiengated framesandrolling Contact means giiidedfer.freereibitaleireulatienthereabeiit,eaehttrame, having guiding means for said rollingcontact ymeans :in-Te1nding; upper;;. andt tlower, guideways, extensible .ieek' meansarranged between vsaidi frames V:for elevating said; roofengagincedevice relative to said,oorlengagitisde: vieltqbrjng said{roof- ,engaging devicerrmlyin .supf portingfengagementgwithgthemine,roof,.and -a powen operated Adevice ort-feedingesaid rst mentioneddevices horizontally insunisonifwhileasaid first. mentioned devicesaresmaintainedfinsupportingxrelaton Withffthe roofeand; oo1,;,andtsaidfrollrig contactameanssgcirculatins freelyt f6 l eleaaasaidagaidiiiaameaiistrelativeate. fSaidefr-anies-durias; suenh ali- Vaiiediwitiifrespeet tQ-the-.lengitudiiial exis the,"I Jaels.

mechanismito -varyfi-thedirectiqn of 4travel v `ol`, said i roofiand.Hoor.. engaging devices.4

3 Arieek1meei1eiiism 21S-Set ferthrineelaim '1 fwhereiiit said poweroperatedieedingdevicej has anchor-:mesmel providing retienen/peintltherefor during thev feedingA Operatieii.;y

4. Afjaclcme`hanism-- as .set forth ingclaimf wherein.- Said`rptiwerfoperated:-devieeehes .means Viet Shifting the.' angular..positiontlrereof; horizontally to-,YarY-.the dire: ,v tion of feedf v 5f111,: amineareeffsiippetting jack mechanism a pair offelongatedxsubstantially coextensiveand superimposed roof,-and, oogengagingIdevices, each ofsaid devicesl including an eleiigetedxframe and rollingeontaetmeans guided forfreeforbitalt circulation thereabout, each iframehaving uidingl means for rsaid rolling contact means ill-E cludingiupperandflowerguideways, extensible jack means` arranged betweenipsaid framesfor elevating said roof engagingdevise.frekitive-te Said iieorv engagingdevice tot brins aseiids.teef.v engaginaffdeviee firmly in Suptwrtiiigvengagement with the mine,roof-, said extensiblejaclr means inclodingfjack, devices arrangedbetween and u longitudinally of isaid-frames and acting on said framesI at points -located inwardly ofthe ends of saiucl r s t-n1entione d devices with saidiirst mentioneddevicesy c .rrwerdlrand rearwardly/with. Arespeet. tesaidv javi?devieesto provide .Substantial overheen. andra pov/er1 Operated f.deyieetferrfeeding Said frstgmentioned de-r vices@ horizontally in` funison while said t rstrmentioned devintrsj aremaintained.insupportingrelation with` the roof andi,oor and said rolling abutment ymeanscirculan ing :freely alongsaid guiding` means relative tolsaidframesduring suc h :horizontalmovement. f

6,In-a mine yroof supportingrjack;fmechanism, apain 0f zeerigatedt;Substantially eoeXteiisivev and-.superimposed roofpgand door fengaging,I devices each of said devices including an elongated frame androllingcontact means, guided for free circulationthereahoutfextensiblejack means arranged between .said1 frames l forelevatingsaid roof, engaging device relative to saidgoor engaging devicet0, bringsid reef engaging device firmly iii-,supporting en: sagement.with the mine Yreoffsaid extensible jack means including jack devicesarranged between andspaedlongi; tudinallyof said frames andacting onsaidf-r-ames at points located inwardly of the ends of saidrstmentioneddevices with.-saidiirst mentioneddeviees projecting forwardly .andrearwardly with respect to v4said ;jac k devieeS; t0 ,prov id e,substantial overhang, -and a power` operated -devicef;forfeedingsaidfirst mentioned devices,horizontallyginzuni-A son while said firstmentioned dev ices. aregmaintained; in supporting relation withthe roofand floo'nfand, said rollingicontact means circulating` freely` relativeto v-saiid framesduring such horizontal movementyandfsaid poweroperatedldevicearranged longitudinally of saidv first mena tioneddevices between said longitudinally spaced jack devices `andoperativelyconnectedto oneof the latterv 7.fln a vmine roof supporting jackmechanism,v a pain of elongated, substantially coextensiveandsuperimposedroofv and .floort engaging devices, each'of saidrdevicesincluding an elongated frame androlling contactv means guided4for free circulation thereaboutf said rolling con.l tact means eachyhaving. guideways therefor extendingaboutzthe frame-margin. andincluding atseriesiof rollers rotatable .about axes transverse 4to therameand means, for lconnecting said rollers for movement in an `orbitalpath ahonty said. 1 guideways: extensiblegiack means...1 arf. rangedbetween said frames for elevatingsaid; groofrena seeing;derieerrelativeftdsaidaileer.engagingrdevieerto bring said roof engagingdevice vfirmly in supporting engagement with the mine roof, and a poweroperated device for feeding said first mentioned devices horizontally inunison while said first mentioned devices are maintained in supportingrelation with the` roof and floor, and said rolling contact meanscirculating freely relative to said frames during such horizontalmovement.

8. In a mine roof supporting jack mechanism, a pair of elongated,substantially coextensive and superimposed roof and floor engagingdevices,feach of said devices including an elongated frame and rollingcontact means guided for free circulation thereabout, extensible jackmeans arranged between said frames for elevating said roof engagingdevice relative to said fioor engaging device to bring said roofengaging device firmly in supporting engagement with the mine roof, saidrolling contact means each having a guideway therefor extending about aframe-margin and including a series of rollers rotatable about axestransverse to the frame, shafts on which said rollers are journaled andflexible means for connecting said shafts for movement in an orbitalpath about said guideway, and a power operated device for feeding saidfirst mentioned devices horizontally in unison while said firstmentioned devices are maintained in supporting relation with the roofand floor, and said rolling contact means circulating freely relative tosaid frames during such horizontal movement.

9. In a mine roof supporting jack mechanism, a pair of elongated,substantially coextensive and superimposed roof and floor engagingdevices, each of said devices including an elongated frame and rollingcontact means guided for free circulation thereabout, extensible jackmeans arranged between said frames for elevating said roof engagingdevice relative to said floor engaging device to bring said roofengaging device firmly in supporting engagement with the mine roof, saidrolling contact means each having a guideway therefor extending about aframe-margin and including a series of rollers rotatable about axestransverse to the frame, shafts on which said rollers are journaled andflexible means for connecting said shafts for movement in an orbitalpath along said guideway, said flexible means comprising an endlesscable and means being provided for attaching said shafts at intervals tosaid cable, and a power operated device for feeding said first mentioneddevices horizontally in unison while said first mentioned devices aremaintained in supporting relation with the roof and floor, and saidrolling contact means circulating freely relative to said frames duringsuch horizontal movement.

l0. In a mine roof supporting jack mechanism, a pair of elongated,substantially coextensive and superimposed roof and floor engagingdevices, each of said devices including an elongated frame and rollingcontact means guided for free circulation thereabout, extensible jackmeans arranged between said frames for elevating said roof engagingdevice relative to said floor engaging device to bring said roofengaging device firmly in supporting engagement with the mine roof, saidrolling contact means each having a guideway therefor extending about aframe-margin and including a series of rollers rotatable about axestransverse to the frame, shafts on which said rollers are journaled andflexible means for connecting said shafts for movement in an orbitalpath along said guideway, said flexible means including parallellaterally spaced endless cables arranged at the sides of the frame andthere being means for attaching said shafts at their ends to said cablesat intervals along their lengths, and a power operated device forfeeding said first mentioned devices horizontally in unison while saidfirst mentioned devices are maintained in supporting relation with theroof and floor, and said rolling contact means circulating freelyrelative to said frames during such horizontal movement.

1l.` In a mine roof supporting jack mechanism, a floor engaging devicecomprising elongated parallel side frames and means for connecting saidside frames in rigid transverse relation, a roof engaging device com-Vprising elongated, upper, parallel side frames and means for connectingsaid side frames in rigid transverse relation, said upper side framesbeing arranged in parallel, superimposed, and substantially coextensiverelation with said lower side frames, rolling contact means guided forfree circulation about each of said frames, and jack mechanisms spacedapart longitudinally of said frames and arranged between said upper andlower connecting means and engaging the same intermediate said sideframes for elevating said roof engaging device relative to said floorengaging device to bring said roof engaging device in firm supportingrelation with the roof.

l2. ln a mine roof supporting jack mechanism, a floor engaging devicecomprising elongated parallel side frames and means for connecting saidside frames in rigid transverse relation, a roof engaging devicecomprising upper, elongated, parallel side frames and means forconnecting said side frames in rigid transverse relation, said upperside frames being arranged in parallel, superimposed, and substantiallycoextensive relation with said lower side frames, rolling contact meansguided for free circulation about each of said frames, jack mechanismarranged between said upper and lower connecting means and engaging thesame intermediate said side frames for elevating said roof engagingdevice relative to said oor engaging device to bring said roof engagingdevice in firm supporting relation with the roof, and power operatedmeans for moving said devices horizontally in unison while said devicesare maintained in supporting relation with the roof and floor, and saidrolling abutment means circulating freely relative to said frames duringsuch horizontal movement.

13. ln a mine roof supporting jack mechanism, a licor engaging devicecomprising elongated parallel side frames and means for connecting saidside frames in rigid transverse relation, a roof engaging devicecomprising upper, elongated, parallel side frames and means forconnecting said side frames in rigid transverse relation, said upperside frames being arranged in parallel, superimposed, and substantiallycoextensive relation with said lower side frames, rolling contact meansguided for free circulation about each of said frames, jack mechanismarranged between said upper and lower connecting means and engaging thesame intermediate said side frames for elevating said roof engagingdevice relative to said floor engaging device to bring said roofengaging device in firm supporting relation with the roof, and poweroperated means for moving said devices horizontally in unison while saiddevices are maintained in supporting relation with the roof and floorand said rolling contact means circulating freely relative to saidframes during such horizontal movement, said transverse connecting meansconnected to said side frames at longitudinally spaced points and saidjack mechanism including a pair of jack devices connected between saidtransverse connecting means at each end of said first mentioned devices,and said first mentioned devices extending forwardly and rearwardly asubstantial distance with respect to said jack devices to providesubstantial overhang.

14. In a mine roof supporting jack mechanism, a floor engaging devicecomprising elongated parallel side frames and means for connecting saidside frames in rigid transverse relation, a roof engaging devicecomprising upper, elongated, parallel side frames and means forconnecting said side frames in rigid transverse relation, said upperside frames being arranged in parallel, superimposed, and substantiallycoextensive relation with said lower side frames, rolling contact meansguided for free circulation about each of said frames, jack mechanismarranged between said upper and lower connecting means and engaging thelatter intermediate said side frames for elevating said roof engagingdevice relative to said oor engaging device to bring said roof engagingdevice in firm supporting relation with the roof, and power operatedmeans for moving said rst mentioned devices horizontally in unison whilesaid first mentioned devices are maintained in supporting relation withthe roof and oor, and said rolling contact means circulating freelyrelative to said frames during such horizontal movement, said transverseconnecting means connected to said side frames at longitudinally spacedpoints and said jack mechanism including a pair of jack devicesconnected between said transverse connecting means at each end of saiddevices and said rst mentioned devices extending forwardly andrearwardly a substantial distance with respect to said jack devices toprovide substantial overhang, and said power operated means including ahorizontal jack device arranged longitudinally of said rst mentioneddevices intermediate said jack devices and operatively connected to oneof the latter. v

15. In a mine roof supporting jack mechanism, a pair of elongated,substantially coextensive and superimposed roof and floor engagingdevices, each of said devices including an elongated frame and rollingcontact means guided for free circulation thereabout, extensible jackmeans arranged between said frames for elevating said roof engagingdevice relative to said door engaging device to bring said roof engagingdevice firmly in supporting engagement with the mine roof, andextensible jack means having anchor means and operatively connected toone of said rst mentioned jack means for feeding said roof and doorengaging devices horizontally in unil0 son while said devices aremaintained in supporting relation with the roof and floor, and saidrolling contact means circulating freely relative to said frames duringsuch horizontal movement.

16. In a mine roof supporting jack mechanism, a pair of elongated,substantially coextensive and superimposed roof and oor engagingdevices, each of said devices including an elongated frame and rollingcontact means guided for free circulation thereabout, extensible jackmeans arranged between said frames for elevating said roof engagingdevice relative to said floor engaging device to bring said roofengaging device rrnly in supporting engagement with the mine roof, saidextensible jack means including jack devices arranged between and spacedlongitudinally of said frames and acting on said frames at pointslocated inwardly of the ends of said first mentioned devices with saidrst mentioned devices projecting forwardly and rearwardly with respectto said jack devices to provide substantial overhang, and extensiblejack means having anchor means and operatively connected to one of saidfirst mentioned jack means for feeding said rst mentioned deviceshorizontally in unison while `said first mentioned devices aremaintained in supporting relation with the roof and oor, and saidrolling abutment means circulating freely relative to said frames duringsuch horizontal movement.

References Cited in the le of this patent UNITED STATES PATENTS1,588,987 OToole June 15, 1926

